[jira] [Commented] (KYLIN-3934) sqoop import param '--null-string' result in null value become blank string in hive table

["Shaofeng SHI (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KYLIN-3934?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16812382#comment-16812382 ] 

Shaofeng SHI commented on KYLIN-3934:
-------------------------------------

Hao, would you like to raise a PR to Kylin? Thank you!

> sqoop import param '--null-string' result in null value become blank string in hive table
> -----------------------------------------------------------------------------------------
>
>                 Key: KYLIN-3934
>                 URL: https://issues.apache.org/jira/browse/KYLIN-3934
>             Project: Kylin
>          Issue Type: Bug
>          Components: Others
>    Affects Versions: v2.6.0
>            Reporter: wanghao
>            Priority: Major
>             Fix For: v2.6.2
>
>
> when column value from jdbc is null, sqoop will write it into hive table with blank string.
> eg 
> jdbc:
> A | B
> 1 | 1
> 2 | 2
> a | null
>  
> hive table:
> A | B
> 1 | 1
> 2 | 2
> a |
> because of this, when I use count(distinct B), it return 3, not 2, and it can lead to other problems
>  
>  
> {code:java}
> String cmd = String.format(Locale.ROOT,
> "%s/bin/sqoop import" + generateSqoopConfigArgString()
> + "--connect \"%s\" --driver %s --username %s --password %s --query \"%s AND \\$CONDITIONS\" "
> + "--target-dir %s/%s --split-by %s --boundary-query \"%s\" --null-string '' "
> + "--fields-terminated-by '%s' --num-mappers %d",
> sqoopHome, connectionUrl, driverClass, jdbcUser, jdbcPass, selectSql, jobWorkingDir, hiveTable,
> splitColumn, bquery, filedDelimiter, mapperNum);
> {code}
> the param '–null=string' should be '
> \\N' instead of blank string ''.
> I resolved this problem by replace the param. But it needs be configured in kylin.properties
>  
>  
>  



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